British military commanders invested much time and effort converting the entire Rock into a huge limestone fortress. Every available nook and cranny was effectively converted into a defensive position to deter any potential attack from any direction, whether by land or sea. The rocky knoll overlooking Camp Bay was no different.
After 1704, the old Moorish walls, badly neglected during the Spanish period, were repaired and improved and a gun battery – the 9th Rosia Battery – consisting of two 18-pounder and 12-pounder guns was placed strategically on the rocky knoll that dominated both Camp Bay and Rosia Bay. By 1744, there were over 20 guns covering Rosia Bay - a small but strategically natural harbour for the British fleet as it was well out of range from Spanish mainland batteries.
The battery was first referred to as Parson’s Lodge Battery in 1771. The name for this battery was probably in reference to the hermitage of St. John the Green (San Juan el Verde) which stood in the area of the Vineyards. Another hermitage, known as Los Remedios, situated on the site of the Old Naval Hospital may have also contributed to the colloquial name. A panoramic sketch by Flemish topographical artist Anton van Wyngaerde shows two towers on the rocky knoll – known as Los Remedios and San Juan el Verde. The hermitages of Los Remedios and San Juan el Verde can be seen just behind these towers, hence the name given to the knoll. A third much larger tower known as La Torre del Tuerto can be seen further South.